iStockphoto/Thinkstock(SEOUL, South Korea) -- North Korea is warning South Koreans there will be “strong physical counter-measures” taken if South Korea participates in the tougher sanctions recently passed by the United Nations.

The threat comes after North Korea announced plans for new nuclear tests and multiple rocket launches targeting the U.S.

China, North Korea’s key ally in the region, warned leaders there that if a test or launch takes place it will stop providing energy and key food aid.

American intelligence indicates a test could take place at any time. North Korea has not given a specific date.